All season long, I've been tweeting about GPAs when I've come across interesting practices at high schools. Admission officers don't have a strong opinion about what methodology is best. We know that your high school or district develops a system of assessment that they determined to be ideal for their environment. All we ask is that they explain that system in the high school profile.
The high school profile is a document that the school counselor sends to us along with your transcript. These documents go over important characteristics of the school, the hierarchy of the curriculum, grading scale, and the methodology used to calculate things like GPA and rank (plenty of schools stopped reporting rank to colleges, so we don't see rank on all transcripts anymore). The profile also explains any restrictions that might come into play when students register for courses.
GPA is not the major factor in our review. Methodologies differ so much that it's impossible to know an applicant's academic story from the GPA. Two students with identical GPAs could have very different coursework and grades on their transcripts. This is why we talk about the transcript being the most important factor in understanding your academic preparation. The GPA attempts to summarize the work you've done, but we use the courses and grades on the transcript to fully understand your academic strength.
Here are some of those tweets I mentioned...
As always, I'm happy to chat in the comments!